Disk drives are commonly used to store large amounts of data in a readily available form. Typically, the primary components of a disk drive are a head disk assembly and a printed circuit board assembly (PCBA) which, when fixed to one another, form a functional unit that is then connected to a computer. The head disk assembly includes a head, an actuator arm, and a data storage disk that is rotated near the head by a spindle motor so that read/write operations may be performed on the disk.
A widely used measure of performance of a disk drive is the number of I/O operations performed by the disk drive. As such, it is essential that factors that adversely interfere with such operations be removed or reduced to within acceptable limits. One such adverse factor is rotational vibration. Rotational vibration can be induced due to a number of factors, such as when other disk drives in the same chassis spin or perform seek operations, or external forces on the rack or chassis containing the drive. When rotational vibration exceeds acceptable limits of a drive's tolerance, the head may be shaken off-track during the read/write operations, causing delays in the scheduled operations of the drive and resulting in overall performance degradations.
To reduce the effects of the rotational vibration, sensors are mounted on the disk drive, such as on the PCBA, to detect induced rotational vibration. Currently, linear sensors are preferred over rotary sensors in today's competitive market because of their significantly lower cost. The use of linear sensors, however, is not without shortcomings as it may require screening of sensors to minimize gain differential between sensors and a relatively close alignment of each sensor's sensitivity axis to reduce the occurrence of an apparent gain mismatch between the sensors. A gain mismatch can reduce the reliability of the data received from the sensors.
Accordingly, what is needed is a method for improving the cost and reliability associated with the use of linear sensors in disk drives.